XPS analysis of FIB-milled Si

The development of focused ion beam (FIB) workstations with beam sizes \u3c 10 run in diameter has initiated a revolution in the modification and characterization of materials on a nanoscale. Focused ion beams are now widely used to obtain site-specific specimens for scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, but are being utilized also in connection with Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS). In order to understand the structure/property relationships of new materials, it is imperative that nano-characterization techniques with site-specific precision be available. In this work, x-ray photoelectron spectroscopy and imaging are used to study the surface changes that occur due to FIB milling of Si(100). The FIB-prepared specimen was analyzed \u27as received\u27 and after the specimen was stored at room temperature and in the atmosphere for 5 months. The XPS images were acquired to determine the distribution of Si4+ (SiO2) and Ga contamination on the Si-0 surface. Small-area XPS spectra of the Si FIB specimen were collected to evaluate the changes in SiO2 surface concentration. The XPS spectra were also extracted from areas similar to1 mum x 1 mum by exploiting the images-to-spectra approach to XPS analysis. This study demonstrates both the problems inherent in the analysis of small samples and the critical information that can be obtained from high spatial resolution XPS analysis. In this example, increased SiO2 Was observed in the \u27aged\u27 sample relative to the \u27as-received\u27 sample, and non-uniform Ga contamination was detected. Copyright (C) 2002 John Wiley Sons, Ltd